My honda 5.5 gx160 generator wont start

If you filled the fuel tank with gasoline enhanced with ethanol the fuel may be bad and caused the carburetor to gum up. Also Honda engines have a low oil sensor and from your description of the oil, can cause problems with the sensor and the engine won't start. Try changing the oil first and then adding a small engine gasoline additive that helps with stale gasoline starting problems.

Try it with a full tank of fuel, the fuel primer is often near the top of the tank on mowers.

check oil level .low oil causes vacuum in the carb, causing fuel starving .
also check capasator has not blown in generator .

Check fuel pump relay.
Check fuel pump control cirucuit.
Check fuel pump/

How about the carb was it cleaned ???? It's definitely a fuel issue

check valve clearances

what about the linkage between the governer and the carb. Is that working and not binding?

If plug is fouled, that would explain running rought and some smoking. But for something to happen all of a sudden, I would suspect bad fuel, which can cause fouled plugs.

I would look for the fuel filter. Blow it our. I know you have a new tank of gas, but you might want to empty it out and make sure the clean and put in new. Even with Stabil in the gas you might just have to much condensation in the tank

Sounds like fuel flow is restricted.
Is the vent cap on the gas tank clear?
Pull the fuel hose off at the carb and let run into a container from the tank......is fuel flow good while filling a cup or two worth of fuel?
If not check filter at fuel switch or at hose connection at tank for restriction.
It takes about 2 minutes to use up fuel in the carb with engine running.
Sure sounds like a fuel problem.